I am continuing my attempt to model a fuel cell with CFX 5.6. Here is my current multicomponent problem:

If I want to remove a certain amount of only one species, I have to use a mass sink. Unfortunately this means I take out some of every species. To counteract this, I wrote some User FORTRAN to figure out how much of the other species come out with my mass sink and I want to then use a mass source (where I can specify a certain mass fraction) to replace the species that were supposed to remain.

So I need to define a mass sink and a mass source on the same Sub-domain. CFX 5.6 will not allow me to do this:

ERROR There is an inconsistency in the problem definition. The location of a number of subdomains overlap. This is not allowed in the current version of the software.